HOLT Electricians Practice Exam

Areas with airborne combustible dust classified under normal operating conditions belong to which category?

1. Class II Division II

2. Class I Division I

3. Class II Division I

4. Class III Division I

The correct answer is: Class II Division I

Combustible dusts are materials that can cause an explosion when suspended in the air under certain conditions. In the classification of hazardous locations, areas where airborne combustible dust is present during normal operating conditions are classified under Class II. Within this class, there are further divisions that specify different levels of risk based on the likelihood and conditions of dust accumulation. In this context, Class II Division I indicates a location where combustible dust is present in the air continuously, while Class II Division II refers to areas where combustible dust is not normally in the air but may accumulate intermittently. The correct answer, which is Class II Division I, specifies that the hazardous conditions with airborne combustible dust can be present at any time, not just under abnormal conditions. This classification system is essential for determining appropriate safety measures and equipment requirements to mitigate the risk of explosion due to combustible dust. Understanding these categories helps electricians and safety professionals ensure compliance with applicable safety standards and regulations.